The invention relates to method and apparatus for harvesting seeds from the cones of a coniferous tree.
Collection of seeds from the cones of coniferous trees is required for reforestation.
The cones are concentrated in the top third of the trees. These trees can grow to significant heights. For example, white spruce trees grow to a height in the order of 80-150 feet.
The time period for harvesting the seeds is short. Typically, they must be harvested in August within a time frame of about 4 to 14 days.
The most commonly used prior art method known to us, for harvesting coniferous seeds for reforestation, involves:
felling the tree while the cones are still closed;
removing the branches carrying the closed cones and transporting them to a central location;
separating the closed cones from the branches, either manually or with an appropriate machine;
packing the closed cones into bags and conveying them in refrigerated containers to a separation facility; and
recovering the seed in a seed extraction plant.
The containers are refrigerated because, if the sun warms the cones, the germination achieved with recovered seed can be deleteriously affected.
In a variation of this system, a helicopter is used to lower a conical harvester over the tip of the tree. The harvester is equipped with a powered rotor having fingers which will sever the branches from the trunk. The branches are recovered into an attached receptacle. The entire assembly is then immediately removed and flown to the central location where the cones are recovered from the branches and processed as previously described.
This prior art system is characterized by several problems or shortcomings. More particularly:
the seeds tend to have lower germination if picked prematurely. This means that the period of time available for optimum harvesting is narrowly limited, as previously mentioned;
the process is labor intensive;
the work to be done is compressed into such a short time period that one has to use several helicopters and crews to harvest seeds from a large number of trees;
the productivity of a helicopter and its supporting crew at the central location is affected by the number of cones on the trees being harvested; and
the germination results obtained from seeds recovered in this manner are typically uncertain since the best germination results are obtained when the seeds are fully mature.
In one aspect of the invention, a seed harvester device is provided. This device is adapted to seat on the conical upper end of a coniferous tree. It is referred to by us as a xe2x80x9cpodxe2x80x9d and comprises:
a generally conical, open-bottomed, hollow housing having a permeable side wall, at least partly formed from material, such as mesh or netting, having openings small enough to retain or prevent the passage therethrough of airborne seeds produced by the cones on the tree, but operative to enable penetration therethrough of sunlight, wind and rain;
the base of the housing internally supports means, preferably forming an open-topped annular trough or receptacle, for intercepting and collecting dropping seeds;
the housing being connected with means for engaging a retrieval device, such as a cable extending from a helicopter or the hook of a xe2x80x98cherry pickerxe2x80x99 machine, so that the pod may be positioned on or retrieved from the tree.
More preferably, the pod comprises:
an open-sided conical frame, such as one formed by top and bottom rings connected by struts, supporting the netting; and
a slanted, generally conical, short wall projecting inwardly and upwardly from the bottom ring to form the annular trough for intercepting and collecting downwardly dropping seed.
In another aspect, the invention is concerned with a method comprising:
harvesting airborne seeds produced by the cones of a coniferous tree, by:
providing a pod having an open-bottomed conical housing, adapted to seat on the upper end of the tree, the housing having a permeable side wall operative to retain the seeds when they are airborne while enabling penetration therethrough of natural elements such as wind, rain and sunlight, and first means, carried internally by the housing adjacent its base, for intercepting and collecting dropping seed;
positioning the pod over the upper end of the tree at a time prior to when the tree""s cones open and the contained seeds mature, release and become airborne;
maintaining the pod on the tree as the cones open and the seeds become airborne, so that the seeds are contained by the side wall and drop and are intercepted and collected by the first means; and
retrieving the pod from the tree after the seeds have been collected, to recover the seeds therefrom.
The method of the invention is characterized by a number of advantages. More specifically:
firstly, a multiplicity of pods may be positioned on trees in a sequential manner over an extended period prior to the seed maturing season using a single machine, such as a helicopter or cherry picker. Similarly, the pods can be retrieved over time after the seed maturing season has ended. The time constraint inherent in the prior art process, arising from having to harvest the seeds from a number of trees in a very short time period, has been resolved;
secondly, our testing has indicated that the germination rate for the fully mature seeds collected in accordance with the invention is higher than that obtained by the previously described prior art technique. More specifically, it appears that seeds that have matured in a cone on the tree and have been collected after the cone opened and they became airborne yielded higher germination than seeds collected in accordance with the described prior art technique; and
thirdly, the manpower needs for harvesting in accordance with the invention are less than is the case for harvesting in accordance with the described prior art technique.